PROJECT SUMMARY/ABSTRACT Hysterectomy is one of the most common surgical procedures in the U.S. About 600,000 U.S. women undergo hysterectomy each year, and about half of these women also undergo bilateral oophorectomy. There is concern that some of these procedures are not medically indicated. African American women are much more likely than white women to have gynecologic surgery, particularly at younger ages. Bilateral oophorectomy results in abrupt loss of ovarian function. Evidence suggests that hysterectomy may lead to impaired ovarian function. Little is known about the long-term effects of bilateral oophorectomy and hysterectomy on health outcomes. Based on limited epidemiologic data, bilateral oophorectomy has been associated with a reduced risk of breast cancer but an increased risk of colorectal cancer, lung cancer, cancer mortality, and all-cause mortality. The effect of hysterectomy with retention of one or both ovaries on long-term health outcomes is less clear. Studies to date on the relation of oophorectomy and hysterectomy to cancer incidence and mortality have included few African American women, and none has reported separately on this population group. We will use data from the Black Women's Health Study (BWHS), an ongoing cohort study of 59,000 African American women, to address the hypothesis that bilateral oophorectomy and hysterectomy influence cancer incidence and mortality. Specifically, we propose to prospectively examine the relation of bilateral oophorectomy and hysterectomy with retention of one or both ovaries to incidence of the most common cancers in women (breast, colorectal, and lung) and to cancer mortality and all-cause mortality. Women were enrolled in the BWHS in 1995 and have been followed biennially by mailed questionnaire. History of gynecologic surgery has been ascertained at baseline and on each follow-up questionnaire. An estimated 1,925 breast cancer cases, 370 colorectal cancer cases, 360 lung cancer cases, 855 cancer deaths, and 2,425 total deaths will contribute to analyses in follow-up from 1995-2011. Given that loss of ovarian function earlier in life may have a more considerable effect on long-term health, and that African American women are most likely to have gynecologic surgery at younger ages, we will further investigate whether age at surgery influences the relation of oophorectomy or hysterectomy to cancer incidence and mortality. In addition, we will also assess whether use of menopausal hormones influences the relation of oophorectomy and hysterectomy to cancer incidence and mortality. This will be the first study to examine the relation of bilateral oophorectomy and hysterectomy to cancer incidence and mortality among African American women. It is particularly important to elucidate the long-term health effects of bilateral oophorectomy and hysterectomy in this population of women because of the high prevalence of these surgeries. PUBLIC HEALTH RELEVANCE: PROJECT NARRATIVE Bilateral oophorectomy has been linked to increased cancer mortality. African American women are much more likely than white women to have these gynecologic surgeries, particularly at younger ages. The proposed study will provide much needed information on the relation of bilateral oophorectomy and hysterectomy to cancer incidence and mortality among African American women, allowing clinicians and patients to make more informed decisions regarding the long-term health risks and benefits of bilateral oophorectomy and hysterectomy.